关键词: 切削机理, 切削模型, 损伤抑制, 碳纤维增强树脂基复合材料(CFRP), 纤维变形

Abstract: Carbon fiber reinforced plastic (CFRP) consists of fiber, matrix, and interface at micro level. Meanwhile, it has laminated feature and shows heterogeneous anisotropy at macro level. The essence of the CFRP removal in machining is the complex process including simultaneous failure of the high-strength fiber and low-strength matrix under cutting force and heat, which results in machining damage easily. Analyzing the material removal process deeply is the key to reveal the machining mechanism of the CFRP, which can help to control the machining damage. The material removal process is mainly determined by the facture process of the fiber due to the fact that the fiber bears main load during the CFRP machining. Therefore, a micro-mechanical model of cutting a single fiber is proposed by analyzing the stress state of the fiber based on the two-parameter elastic foundations to describe the fiber fracture process exactly. In order to represent the stress state of the single fiber accurately, the model is considered the normal and shear effect on the fiber deformation, and the property change of the epoxy as well as interface with respect to temperature. The machining mechanism of the CFRP is revealed as follows:the depth of fiber deformation is influenced by the cutting depth and the fiber orientation. The depth of fiber deformation is increased with the increase of the cutting depth, which will result in machining damage more easily. And the depth of fiber deformation decreases with the increase of the fiber orientation. In order to verify the proposed model, the micro-mechanical model of cutting a single fiber is acquired to calculate the macroscopic cutting force. Then the model is validated indirectly through the comparing of the calculated value of macroscopic cutting force with the experimental value. And the calculation accuracy of the cutting force increases 20% on average because of considering the shear effect and the property change of the epoxy as well as interface with respect to temperature. In addition, the model can reveal the machining mechanism of the CFRP at micro level more accurately and provide theoretical basis for subsequent studies of the damage suppression.

Key words: carbon fiber reinforced plastic(CFRP), damage suppression, fiber deformation, machining mechanism, micro-mechanical model